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0. E. SGRIBNER. TELEPHONE EXCHANGE SYSTEM.

No. 572,221. Patented'Dec. 1, 1896.

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UNIT D STATES PATENT OFFICE.

. CHARLES E. SCRIBNER, or CIIIC'Aeo, ILLINOIS, ASSIGNOR TO THE WESTERNELECTRIC COMPANY, or SAME PLACE.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 572,221, dated December1,1896. Application filed October 16, 1894. Serial No. 626,062. (Nomodeli) To all whom it 1-way concern.-

Be it known that I, CHARLES E. SCRIBNER, a citizen of the United States,residing at Ohicago,'in the county of Cook and State of Illi- 5 nois,have invented a certain new and useful Improvement in Telephone-ExchangeSystems, (Case No. 362,) of which the following is a full, clear,concise, and exact description, reference being had to the accompany- IOing drawings, forming a part of this specification.

My invention relates to switchboards of telephone-exchange systems,particularly to that system in which the act of calling auto- I 5matically brings the signaling substation into connect-ion with theoperators telephone to permit of communication between the operator andsubscriber.

I-Ieretofore it has been common to provide a signaling-annunciator inconnection with each telephone line, the annunciator being provided withswitch contacts adapted to connect the line-circuit with the telephoneof a listening operator when the annunciator was actuated in response toa signaling-current transmitted in the line. The disadvantage of thissystem has been that in the event of several subscribers signalingsimultaneously the different telephone -lines became 0 connected withthe operators telephone at the same time and confusion of the orders tothe operator resulted.

The primary object of my present improvement is to prevent theconnection of 5 more than one line with the operators tele phone at atime. To this end I have so organized the apparatus and circuits thatafter one annunciator has operated and connected the corresponding linewith the telephone of 0 the attendant the operation of the remainingannunciators of the group is rendered impossible until the first callshall have been attended to and the annunciator restored to its normalposition. The call-signals are 5 transmitted from the substations to theexchange by means of a source of signalingcurrent located at theexchange and connected with each line through its particularannunciator, the line being normally open as to continuous currents atthe substation. At the latter station a switch is provided for closingthis circuit when I desired. Hence when the switch of any substation isoperated the corresponding line-annnnciator upon the switchboard at theexchange is actuated and connects the line with the operators telephone.Each annnnciator is provided with a. pair of switch-contacts in additionto the ordinary contacts by which the telephone is connected with theline, which control the continuity of the circuit of the commonsignaling-battery, the switch-contacts of all the annunciators of thegroup being included in series in the battery-circuit. It is thus plainthat when an annunciator has been operated the transmission of a signalfrom any other substation of a group is prevented since the connectionof the other members of the group with a common signaling-battery isinterrupted. '70

Subordinate features of my invention Consist in means for restoring theannunciator of a signaling-line upon the establishment of connectionwith the line by means of the usual connecting-plugs and in a device forcontrolling the connection of the operators telephonewith any lineduring the use of the line. The first of these subordinate objects Iaccomplish by employing the type of annunciatorknown asa self-restoringor self-- resetting annunciator,tl1e restoring-magnet being included ina local circuit which is closed by cooperating contact-pieces at anyspring-jack with which connection may be made by means of a plug, one ofthe contactpieces being preferably located in the springjack itself andthe otherin the connectingplug, the circuit-connections with the latterbeing made by means of the usual flexible cord.

The second-mentioned subordinate feature consists in amanually-controlled key for opening the local Circuit to permit theoperation of the annunciator in order to connect the operators telephonewith the line. Ob- 5 viously if the restoring circuit be thusinterrupted while the line-circuit is still complete at the substationthe annunciator will at once respond to the current flowing from thecommon signaling-battery in the line-circuit mo and will act to connectthe line with the tele phone, as in the case of an individual signal.

. included in the branchwith bell a 7 line-wire 1 is connected with theline-spring position. a by conductor 5 with 'contactd of annunciatorconductor 5, normally, extending from conconnected with their respectivelines while p anyin g drawings and may be described with ing terminalsof all the line-annunciators are all of the line-annunciators beingincluded quired for signaling and for bringing the op My invention isillustrated in the accomreferenee thereto.

Figure 1 represents, diagrammatically, the apparatus and circuits of myimproved exchange system. Fig. 2 is an elevation of theline-annunciator, showingthespeeial switchcontacts with which it isprovided in my in-- vention.

In the diagram of Fig. 1 three substations A, A, and A are representedas connected with a telephone-switchboard by means of line-wires 1, 2,and 3,1espective1y. As the circuit connections of all the lines arealikethose of line to substation A alone may be traced. The substation isprovided with the usual telephone a, microphone to, and bell a togetherwith an automatic switch a for switching the bell and telephonealternately into circuit of theline. A condenser a is The I) of aspring-jack c at the'exchange and with one terminal of the main oroperating magnet d of the line-annunciator e. The remainconnected with acommon conductor 4:, which .terminates in the contact-anvil dof-annunciator e. This anvil is one of two which are crossed together bycontact-piece d on the .annuneiator while the latter is in its normalContact (l of the pair is connected 6, contact (1 of the latter beingconnected in turn with contact (Z of annunciator 6 whose contact d isgrounded through the common signaling-battery Z. Contacts d 01 upon thedifferent annunciators are thus in series in a ductor 4 throughsignaling battery f to earth,

in branches from thecommon grounded battery to their respective lines.

Each annunciator is provided with another pair of, contact-points d d,which are adapted to be closedtogether when the shutter d of theannuneiator is operated. The contacts (Z upon the different annunciatorsare pieces (Z- are united with a common conductor 7, which constitutesone terminal of the operators telephone set g.

Each spring-jack has, in. addition to the, line-spring b, a thimble b,which constitutes one terminal of the restoring-magnet d of thecorresponding line -annuneiator, the other terminal of the magnet beingconnected to earth.

The operator is provided,.as usual, with anumber of pairs ofconnecting-plugs for .uniting two lines into continuous circuit. In thediagram butone pair is represented, togetherwith the various accessoryappliances reerators telephone into connection with the line. Each plug,as h, is provided with a contact-piece 2', adapted to make connectionwith the line-spring b and with a sleeve contact-piece 1', arranged toregister with thimble b of the spring-jack, into which it may beinserted. The tips 1 of the plugs h h of a pair are connected togetherby a flexible conductor 8, twov calling-keys k and It being included inthe circuit, each being adapted to send a signaling-current from thegeneratorl through the corresponding plug when the key is depressed. Thesleeve contact-pieces 2" are connected together by a conductor 9, abranch 10 from which extends to the free terminal of battery f. A key onis included in conductor 9, adapted to open the circuit when depressed.A clearing-out signal 0 of ordinary character is connected in a branchfrom conductor 10 to conductor 8 of the plug-circuit.

The general construction of'annunciator e is represented with sufficientclearness in the diagram, but Iwilldescribe it in somedetail withreference to Fig. 2.

Magnets 61 and d may be ofthe tubular type, with their closedextremities placed together. The shell of magnet 01 carries a bracket(1", provided with trunnions, upon which an armature (Z is pivoted,being hung from its upper edge. The shell of magnet d likewise carries abracket d, in which a shutter (Z is pivoted at its lower edge. Beforethe shutter hangs a light shield d,.whieh is thrown into a horizontalposition by the shutter when the latter falls forward. The shutter isnormally engaged and held in its vertieal position by a catch at theextremity of an arm (Z carried by armature (Z The two contact-points d dare carried in a plate of insulating material secured to the bracket.They arecrossed together while the shutter is in-its normal position bya light strip of metal d, fastened to the shutter and adapted to bearagainst them. The contact-points d d arearranged on the lower part ofthe bracket (Z in the manner of the ordinary night-bell springs, thespring (1 being in position to been gaged by the shutter in its falloutward and to be closed upon by d. hen the magnet (Z is excited, itattracts its armature d and thus releases the shutter (1 The latterfalls outward, throwing the shield (1 into its horizontal position andat the same time removing the cross between anvils d d and closingcontacts (Z (1 together.

I will now trace the operation of the system throughout-with referenceto Fig. 1. In the normal condition of the apparatus the circuitcontact-points d d and conductor '7 to the at the substation. Theannunciator is thus operated and displays its signal, at the same timeclosing a circuit from the line through operators telephone set 9. Thesubscriber then, addressing the listening operator at the exchange,communicates the order for the connection which he desires. The operatorinserts plug h into the spring-jack c of the calling-line and places theremaining member 71, of the pair of plugs in a spring-jack of the linecalled for. Circuit is thus completed between the two lines, being byway of the tips of the plugs and conductor 8 of the plug circuit. I

By the insertion of plug h into spring-jack c the localrestoring-circuit of the annunciator e was closed through a circuit fromgrounded battery f through conductor 10, conductor 9 of theplug-circuit, key m, sleeve "L7 of plug h, thimble b of the spring-jack,

and thence to earth through the restoringmagnet d of the annunciator.This instrument is thus returned to its normal position, the signal isefiaced, the contacts d d are permitted to separate and thus todisconnect the operators telephone set 9 from the line 2,

' and the contacts (Z d are again closed together, completing thecircuit of the signaling-batteryf to conductor 4 and thus makingpossible the transmission of a signal from another substation. Bythe'insertion of plug h in the spring-jack of the line called for therestoring-circuit of that line also is closed, so that its shutter isprevented from falling when the answering subscriber removes histelephone from its switch-hook to enter into conversation.

If at anytime the operator should desire to connect her telephone toline 2, she may depress the key m. The restoring-circuit of annunciatore is thereby interrupted, and since current is still flowing through themagnet cl of the annunciator of that line, the telephone at thesubstation being removed from the switch-hook, the shutter of theannunciator is released and connects the line with the telephone 9.

While the telephones are in use there exists current from battery fthrough clearingout annunciator 0 to conductor 8 and thence to earth atthe substations. iVhen, after the completion of conversation, thesubscribers replace their telephones on their switchhooks, currentthrough the clearing-out signal is interrupted and it gives the signalfor disconnection.

Having thus described my invention, I claim as new and desire to secureby Letters Patent-'- 1. In combination with the telephone-lines of agroup, each provided with means for making connection with it in aswitchboard, a relay in each line normally responsive to currents in theline, a local circuit containing an operators telephone adapted forconnec* tion with any of the lines through the agency of thecorresponding relay, a device actuated in the movement of any relayadapted to prevent the operation of any other relay, at the same time,and mechanism actuated in making connection with the line adapted torestore the said device to its normal-position to permit the subsequentoperation of other relays, substantially as described.

2. The combination with telephone-lines of a group, of a relayin'connection with each line responsive to currents in the line, a localcircuit including an operators telephone adapted for connection with anyline through the agency of the corresponding relay, a circuit controlledby each of the relays to all the other relays adapted when changed byone relay to prevent the operation of the other, electrical mechanism ineach relay adapted to return the relay to its normal position, a circuitincluding said mechanism, and a switch operated in making connectionwith the line controlling the said last-mentioned circuit, substantiallyas described.

3. The combination with each of several telephone-lines, of a commonsource of signaling-current adapted to be closed through any of thelines to signal from the substation to the exchange, an annunciator inthe line, and switch-contacts thereon controlling the connection. of thesource of signaling-current with all the lines, an electrical device forrestoring the relay to its normal position, and a switch actuated inmaking connection with the line controlling the circuit through saiddevice, substantially as described.

4:. The combination with each of several telephone-lines normally openat the substation and including a common source of signalin g-current atthe exchange, of means for closing the line at the substation forsignaling, and an annunciator in each line having switchcontacts adaptedto disconnect the source of signaling-current from all the lines whenthe annunciator is operated, substantially as described.

5. The combination with each of several telephone-lines normally open atthe substations and connected with a common source of signalingcurrentat a central station, of means at each substation for closing thelinecircuit to signal, an annunciator in each line at the centralstation having one pair of switch-contacts adapted, when the annunciatoris operated, to connect its particular line with an operators telephoneand another pair of switch contacts adapted to disconnect the commonsource of signaling-current from all the lines of the group,substantially as described.

6. The combination with a telephone-line, of a self-restoringannunciator in the line together with a source of electric current,switch-contacts controlled by the annunciator adapted to connect theline with an operators telephonewhen it is operated, a local circuitthrough the restoring-magnet, switch-coritaets for closing the same whenconnection is made 1131113116 line, and a key adapted to open the localcircuit, whereby the operators telephone may be brought into connectionwith the line during theme of the line, substantially as described.

In Witness whereof I hereunto subscribe my name this 3d day ofSeptember, A. D1894.

CHARLES E. SORIBNER- Vitnesses:

ELLA EDLER,

LUCILE RUssELL.

